Fuel injection pump for internalcombustion engines



Nov. 5, E946. H. MULLER ETAL ZAQSW FUEL INJECTION PUMP FOR `:IN'L'EIAJ-COMBUSTION ENGINES Filed April 29, 1941 2 Sheets-Sheet 1 H. MULLER ETAL Filed April 29, i941 A2 sheets-sheet 2 ,Kring wam HEI. MU 7' MULL ERAN AN ro/v P/s chf/NG ER Patented Nov. 1946 i sari-:sA PATENT desir FUEL lNJECTIN PUMP FOR INTERNAL- COMBUSTION ENGINES Helmut Mller and Anton Pischinger, Cologne,

Germany; vested in the Alien Property Custodiari i Application April 29, i941, Serai No. 390,902 En Germany April l.23, 194.10

i claim. (ci. ica-4i) The invention relates to a fuel injection pump for internal combustion engines whose pump chamber occupies a. position between'a positively driven pump piston and aspring-loaded equaliz- .ing piston sliding in a longitudinal bore of the pum-p piston, and'is', on the` down stroke of the pump piston, connected with the injection port, by means of an opening in the `piston wall, so that the equalizing piston injects the fuel and by its displacement in the pump piston again breaks the connection.

The invention consists in providing a cavity in the equalizing piston, which, after the equalizing after the completion of the injection, and which remains uninuenced by the pressure conditions prevailing in the pump cpamber after the injection. j

In the drawings is shown by way of example an embodiment of the invention, Fig. 1 showing a longitudinal section of the equalizing pump at the end of the suction stroke, Fig. 2 at the end of the overow operation, Fig. 3 during the fuel injection, Fig. 4 during the pressure relief and Fig. 5 the injection pump in vertical section.

AA pump piston 2, positively reciprocated by a, cam 25, operated by the engine in known way, angularly adjusted by rack and segment 26, and extending into the pump housing i, receives in a longitudinal bore the equalizing piston 3. The pump chamber d is in the interior of pump piston 2. During the downward motion of the pump piston, in which the equalizing piston resting on the.

annular shoulder 5 does not take part,'the pump piston opens the suction port 6 in the pump housing and connects the same, through the annular space the`transverse port 8 and the longitudinal duct 9, with the pumpchamber t (Fig. 1), so that the latter becomes lied with fuel. With the next upward movement of thepump piston, it first closes the suction port B and the transverse port d and carries along, through the medium of the enclosed fuel', the equalizing piston 3, accompanied by increased compression of the euualizing spring iii. Thereby the fuel content of the pump chamber is put under pressure of the equalizing spring. With further continuation of the upward motion of the pump piston, the latter connects the pump chamber With the overflow channel it, by way of longitudinal duct 9, cross bore ii, annular space i2 and opening i3. As a resultl of the consequent drop in pressure, the equalizing piston is moved downward under pressure'of its spring, and thus discharges fuel into the overflow channel it, until the inclined edge i5 of the equalizing piston has moved over the opening i3 in the pump piston (Fig. 2). The pump piston is, in a way well known per se,

revoluble about its longitudinal axis, by means/ of a governor so that, according to the position of the inclined edge over the opening i3, the covering of the latter occurs sooner or later and thereby a. larger or smaller quantity of fuel remains in the pump 'chambenfor the following injection. In the next instant, the pump piston connects the pump chamber with the fuel injection conduit 'i7 (Fig. 3) through longitudinal duct 9, cross bore II, annular space i2 and opening i6. The equalizng piston then moves downward under the pressure oi the equalizing spring vand causes the fuel to be injected until the equalizing piston has covered the opening it by its guide ring or cut-0H edge i8, and at the same time,r or slightly before, its control edge i9 rhas opened the overflow opening 2li, which connects the pump chamber with the overflow channel it. As soon as the cutoff I8 has covered or almost covered the opening i6, the cavity 2i, in the further progress of the downward motion of the equalizing piston, establishes a, direct connection between the injection conduit i1 and the overflow channel it or other low pressure space, so that the injection pressure in the injection conduit drops quickly to the low pressure in the overflow channel (Fig. 4). As this relief is controlled by the injection-controlling equalizing piston, it occurs whatever the machine speed, always in direct sequence to the injection. Inasmuch as a separate relief is provided for the pump chamber through opening 20, the relief of the injection conduit is not delayed by pressure remaining in the pump chamber.

We claim:

-. In a fuel injection pump for internal combustion engines, a hollow pump piston, a pump housing having a. chamber therein in which is received and guided said pump piston for reciproeating movement, means for reciprocating said pump piston, an equalizing piston slidably mounted in said pump `piston and forming therewithv at the inner end of said pump piston a pump chamber, spring means urging said equalizing piston toward said pump chamber, means for admitting fuel 'to said pump chamber, means forming a high pressure injection conduit, and means forming a pressure relief cnnduit, both said conduits communicating with the chamber of the pump housing-and being controlled by said pump piston, said pump piston and said equalizing piston having portmeans therein respectively adapted V- to cooperate to release fuel from said pump chamber into said injection conduit during a certain stage of the movements of said pistons, 10

said pistons also having port means therein retion conduit.

HELMUT MLLER. ANTON PISCHINGER. 

